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South Dakota Department of Transportation
Project Synopsis
SD1999-09


Title: High Volume/High Speed Asphalt Roadway Preventative Maintenance Surface Treatments
Project Researcher: Monte Wade, Applied Pavement Technology
Project Manager: Daris Ormesher
Research Period: 7/1/1999 - 12/31/2000
Status:
Cost: $49,971.00

Problem Statement: South Dakota has had a very aggressive surface seal program. Chip seals and sand seals have been the treatments of choice but they have been less successful on high volume/high speed roadways. Chip retention is the major problem associated with these failures. The high number of broken windshields caused by loose chips has resulted in multiple claims on an individual project.

It is recognized that some form of surface treatment alternative is desired to attain the maximum service life of these asphalt pavements. Alternate methods such as precoated aggregate, slurry seals, fog seals over chip seals, and a variety of other methods need to be considered. The different variables involved with chipseals (aggregates, binders, construction, etc.), as well as alternatives to chip seals need to be researched for possible improvements.

Research is needed to determine what modifications to our current chip sealing practices are necessary to eliminate future occurrences of this type or to suggest alternative technologies, such as slurry seals or open-graded friction courses, which can substitute while still achieving the benefits of a successful chip seal.



Findings: The South Dakota DOT has made extensive use of chip seal and sand seal surface treatments in the maintenance of their AC pavements. Such surface treatments have been found to provide a cost-effective means of extending the life of AC pavements in South Dakota. Although the use of chip seals and sand seals have for the most part been reliable treatments, there have been some notable failures, especially on high-volume, high-speed roadways. This project was undertaken to investigate the use of chip seals for such applications and to make recommendations to improve their performance. This project also involved the development of guidelines for the design and construction of chip seals. To evaluate the use of chip seals in South Dakota, several efforts were undertaken. First, an extensive literature review was conducted to develop an understanding of the latest practices and experiences. Second, interviews were conducted with South Dakota DOT from all departments involved in the chip seal process to investigate their practices and to determine areas for improvement. Finally, test sections were constructed to evaluate the performance of standard and modified chip seal designs. The test sections consisted of 12 chip seal designs and included two aggregate types (quartzite and natural aggregate) and alternate chip seal designs with new gradations and other modifications and enhancements. Based on these efforts, recommendations are provided to improve chip seal performance. In addition, guidelines were developed to select feasible surface treatments for a specific project.

Research Objectives:
1  To develop guidelines to allow proper selection of surface treatments.
2  To develop design guidelines for chip seals.
3  To develop construction guidelines for chip seals.
4  To construct chip seal test sections to validate design and construction guidelines.

Research Tasks:
1  Meet with the Technical Panel to review project scope and workplan.
2  Review and summarize literature pertinent to asphalt surface treatments, paying particular attention to the design and construction of chip seals.
3  Interview department personnel to determine South Dakota‚Äôs current asphalt surface sealing design and construction practices.
4  Evaluate various asphalt surface treatments and determine which are appropriate for South Dakota highways. The evaluation should include but is not limited to other state and agency experience, cost effectiveness, compatibility with materials unique
5  Develop guidelines for a selection process of appropriate asphalt surface treatments for use on highways of all traffic levels in South Dakota. The panel assumes the selection process would include pavement surface condition, available aggregate, equ
6  Provide a technical memorandum describing tasks one through five. This will be due by October 1, 1999.
7  Recommend appropriate chip seal or other surface treatment designs to be constructed and tested in South Dakota, with panel guidance. These designs must be submitted to the technical panel no later than November 8, 2000.
8  Monitor and evaluate the construction of the test sections and document test results obtained during initial construction and periodic on-site evaluations.
9  Prepare guidelines for the design and construction of asphalt surface treatments for use on highways of all traffic levels in South Dakota. The guidelines should include recommendations on aggregate type and gradation, particle size and shape, spread
10  Prepare a final report and executive summary of the literature review, research methodology, findings, conclusions, and recommendations.
11  Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

Documents Available:
SD1999_09_Final_Report.PDF

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